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Is Soy Protein a Healthy Source for Muscle Recovery?

The soy bean

Soy beans have been consumed for thousands of years, especially in Asian Countries. They are one of the first or only ingredients that lots of Minnesota farmers grow, because soy beans are used in many products that consumers buy.

Soy can be found in most processed foods to increase shelf life, in soap to help mix the other ingredients together, in animal feed to provide protein, used as cooking oil in American restaurants dating back to the 1950’s, and is a popular protein source for vegan diets.

Soy beans have a higher fat content than some other options, and uniquely contain phytoestrogens that will increase estrogen production in the body. This has caused some concern in both men and women across America for many years.

Topics of Concern in America

  1. If soy beans increase estrogen in the body, doesn’t that put me at higher risk for increasing body fat, breast growth, lower testosterone levels, and lower sperm count?

  2. Is it effective at triggering protein synthesis, will it allow me to put on muscle mass, and can I recovery quickly from working out if I eat it?

Turns out Soy is a Complete Protein

Whether you are trying to lose body fat and retain muscle mass, put on muscle mass, or add strength everyone seems to agree that you need sufficient proteins that are complete. This is typically found in animal protein sources or whey/casein protein powders. Soy typically has been highlighted that it is lacking in some of the essential amino acids to make it complete and that it won’t be an effective source of protein.

The good news is that SOY PROTEIN IS COMPLETE.

To be a complete protein means that something must contain all 20 essential and non-essential amino acids. Animal protein sources have more of all of these than soy protein which may make them a better option if your protein gram count is going to be limited for the day. Take a look at this chart which shows the breakdown of the amino acids of both animal meats and soy protein.

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Leucine is one of the most important amino acids to look at which is bolded on this chart because it has the ability to signal genes and hormones to turn on protein synthesis. This anabolic engine of the body starts the healing process of muscular tissue and to create new cells in the body. The minimum amount of leucine needed to get this engine started is ~3 grams. It takes 20g of animal protein and 30g of soy protein to surpass the 3g leucine threshold. Keep in mind that these are the minimal doses to get the road to recovery started.

In the aging population they encounter anabolic resistance and have less hormones to secrete. Elderly people will require closer to 40g of animal protein and 60g of soy protein to cross that 3g leucine threshold.

Testosterone prevails against soy

Phytoestrogens are found in many foods, some you maybe didn’t know. These uncommon foods are edamame, coffee, oats, rice, apples, legumes, and many more. This makes them hard to avoid, but is that really necessary? Turns out phytoestrogens are believed to have antioxidant, anticancer, and antiviral properties. They in fact are what makes apples, and some other fruits so healthy for you.

Thanks to Hamilton-Reeves and colleagues who completed a meta-study that was published in the Journal of Fertility and Sterility (2010) showing similar results in 32 studies that testosterone did not decrease even when soy protein was consumed for recovery after a workout.

Some studies showed the contrary but it took consuming 3 liters of soy milk per day for 6-12 months to have the opposite effect on testosterone. That is dedicated soy milk drinking.

Like always everyone responds differently to everything. If you want to see how your body responds to soy, do a testosterone test, consume 30 of 60g of soy protein, wait a couple hours and have a testosterone test done again to see the change.

Want to read more about this topic…check out this article